GPSP is a nifty little piece of software for your PSP. It was created via some circuit hacking and using a piece of PSP software called "Lua."
Using a GPS dongle, you're able to pick up a signal and use the PSP as a full-blown GPS device. It can show your location and update in real time (with a slight delay). Do you need GPSP? No. Is it cool? Sure. So go download it and hack away.
GPSP (GPS front end program for PSP) [PSP Updates]